On the Degrees of Freedom Regions of Two-User MIMO Z and Full Interference Channels with Reconfigurable Antennas

We study the degrees of freedom (DoF) regions of two-user multiple-input multiple-output (MIMO) Z and full interference channels in this paper. We assume that the receivers always have perfect channel state information. We derive the DoF region of Z interference channel with channel state information at transmitter (CSIT). For full interference channel without CSIT, the DoF region has been obtained in previous work except for a special case M-1 < N-1 < min(M-2, N-2), where M-i and N-i are the number of transmit and receive antennas of user i, respectively. We show that for this case the DoF regions of the Z and full interference channels are the same. We establish the achievability based on the assumption of transmitter antenna mode switching. A systematic way of constructing the DoF-achieving nulling and beamforming matrices is presented in this paper.